Some market milestones are meaningful. Others are symbolic. But Cramer has noticed, whenever the market achieves any kind of significant level, skeptics crawl out of the woodwork.

And, with the S&P 500 piercing 2,000 on Monday for the first time ever, Cramer fully expects to hear plenty of bearish predictions in the days ahead.

Even though the S&P pared some of its gains into the close, Cramer doesn't think it will be long before television, newspapers and the Internet are awash with stories about S&P 2000, and how the advance can't be sustained.

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And the arguments may be very convincing with bears invoking geopolitical events, the global economy or the Fed as reasons to fear the market. "For 1,000 points we've heard the Fed is behind the curve and how the Fed is the chief reason why stocks are going up," Cramer said. Don't expect that kind of commentary to die down.

Therefore, "with this important milestone being breached, I think it's vital for investors to separate the facts from the fiction," the "Mad Money" host said. And if the factual catalysts for the advance remain intact, then Cramer thinks it's reasonable to conclude that the market will not change its overall direction,

Digging down into the market, Cramer believes one of the biggest tailwinds has been M&A, motivated by growth.

That is, companies are struggling to grow organically, so they're creating synergy by teaming up.

"Exhibit A: The deal between Tim Horton's and Burger King," Cramer said. "This deal is motivated by growth, pure and simple. And this deal makes a ton of sense as the very global Burger King can help grow the very parochial Tim Horton's internationally."

In this case, Cramer thinks the deal better leverages resources than otherwise possible if the companies remained separate. "They can put a Horton's right next to, or even inside, a Burger King to get morning dollars from a place known for lunch and dinner."

The deal is just one example, but, broadly, Cramer sees no reason to believe that the slew of M&A in the market is going to stop just because the S&P 500 crossed 2000. "Whether in media, retail, rental cars, airlines or industrials, the need to merge and drive growth remains very much intact."

Also Cramer said another major tailwind in the market has involved an aggressive interest in unlocking shareholder value. Sometimes activist investors have agitated for the change, as in the case of ValueAct Capital which prodded for the retirement of Steve Ballmer. Other times the value has been created internally, as was the case with Gannett's decision to spin off its publishing arm.

Either way, Cramer sees no reasons for this phenomenon to end abruptly.

In addition, Cramer has often cited a relatively improving economy, the energy revolution underway in North America, the natural and organic food trends and other themes as powerful tailwinds in the market.

Now, that's not to say stocks won't sell off at all; Cramer thinks they could. "It's certainly true that low rates have kept lots of stock with big dividends from going down, as investors chased yield," Cramer said. If rates go higher, there may be a rotation. Also looking at the advance from a psychological level, Cramer wouldn't be surprised if some investors took gains and locked in profits, "just because."

However, broadly, Cramer doesn't want the gloom-and-doomsayers who often grab the spotlight when stocks hit milestones to distract investors from the fundamentals.

"As we trump S&P 2,000, we have much more than Janet Yellen and Ben Bernanke to thank for this fabulous rally," Cramer said. Quality businesses, good leadership, activist investors, long-term themes and M&A inspired growth are also responsible for the advance.

If you think that's changing, then, you may want to cash out. But if you think those catalysts remain vibrant, Cramer doesn't want the doomsayers to psyche you out.